WiMAX系統同頻干擾研究

STUDY ON CO-CHANNEL INTERFERENCE FOR WiMAX SYSTEM

林峻瑋(Chun-Wei Lin)

指導教授 ： 許超雲

大同大學/電機資訊學院/通訊工程研究所/碩士(2011年)

摘要

電信系統商廣泛使用的蜂巢式系統，藉由縮小發射功率來增加基地台佈建的密度，雖然可以提高系統的容量，但也由於頻率覆用導致同頻干擾問題也越來越嚴重。
本篇論文著眼於分析干擾嚴重的地區，以實測找出訊號低落的位置。並藉由增加頻點的方式改善同頻干擾的問題，經實際測量與分析數據證明可藉由頻點的增加，有效降低同頻干擾，大幅提升訊號品質。
實務上有無法增加頻點的情況，我們以多重智慧天線（Multiple Input/Multiple Ouput；MIMO)技術來改善同頻干擾的影響。本論文亦嘗試在大同大學與阿爾卡特-朗訊(Alcatel-lucent；ALU)於2009年合作建置的WiMAX校園實驗網路中，使用網路應用VoIP與FTP來評估同頻干擾嚴重性。藉由實驗能了解網路中MIMO機制實際運作的情形，得到的數據可以提供作為產品開發或網路維運時的參考依據。
本論文應用增加頻點或應用多重智慧天線，改善同頻干擾問題，並於實測證明其效果。

關鍵字

同頻干擾 ； 多重智慧天線

並列摘要

The operator use's Cellular Network decrease Transmit power to increase the density of Base station and system capacity, but frequency reuse may cause the problem of co-channel interference more serious.
The thesis focuses on investigating the distribution of base station in the area with serious interference to find the position of weak signal. By increasing the bandwidth to improve the problem of co-channel interference, and we can prove that it can decrease the problem of co-channel interference and increase the quality of signal via the actual measurement and the analytical data.
In reality, it is difficult to increase the usable bandwidth so we use Multiple-Input/Multiple-Output(MIMO) to improve the influence of the co-channel interference. In the WiMAX campus experiment network, established in cooperation of Tatung University and Alcatel-Lucent(ALU) in 2009, we use the VoIP and FTP to estimate the influence of the co-channel interference.
By the experiment, we know the MIMO Technology and the real performance. The result can be used by the manufacturers and students for network application and hardware development or the ISP vendor who using the ALU equipment for network maintenance.

並列關鍵字

Co-channel Interference ； MIMO

參考文獻

[1] Jeffrey G. Andrews, Arunabha Ghosh, and Rias Muhamed. Fundamentals of WiMAX: Understanding Broadband Wireless Networking. Prentice Hall, 2007.

[2] M. Tran, D. Halls, A. Nix, A. Doufexi, and M. Beach, "Mobile WiMAX Downlink Performance Analysis with Adaptive MIMO Switching," in Mobile WiMAX Symposium, 2009. MWS '09. IEEE, 2009, pp. 147-151.

[3] M. I. Rahman, E. de Carvalho, R. Prasad, "Mitigation of MIMO Co-Channel Interference Using Robust Interference Cancellation Receiver," in Vehicular Technology Conference, 2007. VTC-2007 Fall. 2007 IEEE 66th, 2007, pp. 531-535.

[6] Qiang Li, Jing Zhu, Qinghua Li, C. Georghiades, "Efficient spatial covariance estimation for asynchronous co-channel interference suppression in MIMO-OFDM systems," IEEE Transactions on Wireless Communications, vol. 7, pp. 4849-4853, 2008.

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